The evolution of a 3rd generation (hereinafter, referred to as “3G”) radio access (evolved universal terrestrial radio access (hereinafter, referred to as “EUTRA”)) scheme and the evolution of a 3G network (evolved universal terrestrial radio access network (hereinafter, referred to as “EUTRAN”)) of cellular mobile communication have been studied in 3G Partnership Project (3GPP).
In 3GPP, the study of a 4th generation (hereinafter, referred to as “4G”) radio access (advanced EUTRA (hereinafter, referred to as “A-EUTRA”)) scheme and a 4G network (advanced EUTRAN) of cellular mobile communication has been initiated. In A-EUTRA, those corresponding to a wider band than that of EUTRA and compatibility with EUTRA have been studied, and the communication of a base station device of A-EUTRA with a mobile station device of EUTRA using part of a frequency band of A-EUTRA has been proposed.
A layered orthogonal frequency division multiple access (OFDMA) scheme that performs communication using multiple frequency bands, which is multi-carrier transmission, for a downlink from a base station device to a mobile station device in A-EUTRA has been proposed. Also, for an uplink from a mobile station device to a base station device in A-EUTRA, switching of a single carrier-frequency division multiple access (SC-FDMA) scheme, which is single-carrier transmission, and the OFDMA scheme, which is multi-carrier transmission, and communication using multiple frequency bands as in the downlink have been proposed (Non-Patent Document 1).
FIG. 27 is a diagram showing a schematic structure of channels in EUTRA. A base station device BS1 wirelessly communicates with mobile station devices UE1, UE2, and UE3. A downlink of wireless communication from the base station device BS1 of EUTRA to the mobile station devices UE1, UE2, and UE3 includes a downlink pilot channel, a downlink synchronization channel, a broadcast channel, a downlink control channel, a downlink shared data channel, a control format indicator channel, a Hybrid Automatic Repeat reQuest (HARQ) indicator channel, and a multicast channel. In HARQ, an error is controlled by combining Automatic Repeat reQuest (ARQ) with an error correction code of turbo coding or the like. In HARQ using chase combining (CC), the retransmission of the same packet is requested if an error is detected from a received packet. Reception quality is improved by combining the two received packets. In HARQ using incremental redundancy (IR), error correction capability is enhanced by decreasing a coding rate when the number of retransmissions is increased since redundant bits are divided and sequentially retransmitted bit by bit.
An uplink of wireless communication from the mobile station devices UE1, UE2, and UE3 of EUTRA to the base station device BS1 includes an uplink pilot channel, a random access channel, an uplink control channel, and an uplink shared data channel.
FIG. 28 is a diagram showing a schematic configuration of an uplink radio frame in EUTRA (Section 5.2 of Non-Patent Document 2). For example, FIG. 28 shows a schematic configuration of a subframe of a radio frame when an uplink control channel and an uplink shared data channel are frequency-multiplexed. In FIG. 28, the horizontal axis is a time axis and the vertical axis is a frequency axis. An uplink radio frame includes multiple physical resource block (PRB) pairs. The PRB pair is a unit of radio resource allocation or the like, and includes a frequency band (PRB bandwidth) and a time band (2 slots=1 subframe), which have predetermined widths. Basically, 1 PRB pair includes 2 PRBs (PRB bandwidths×slots) which are continuous in a time domain.
In an uplink subframe, 1 PRB includes 12 subcarriers in a frequency domain, and includes 7 SC-FDMA symbols in the time domain. A system bandwidth is a communication bandwidth of a base station device. In the time domain, there are a slot including 7 SC-FDMA symbols, a subframe including 2 slots, and a radio frame including 10 subframes. A unit including 1 sub-carrier and 1 SC-FDMA symbol is referred to as a resource element. In the uplink radio frame, multiple PRBs corresponding to the system bandwidth are arranged in the frequency direction.
In each subframe of the uplink, at least an uplink shared data channel that is used in information data transmission and an uplink control channel that is used in control data transmission are arranged.
In FIG. 28, the uplink control channel is arranged in two ends of the system band, that is, a first PRB and a last PRB when viewed from a low frequency side. These resource blocks are hatched and shown. There is shown the case where uplink shared data channel is arranged in other PRBs, but the number of PRBs in which the uplink control channel is arranged is varied in a subframe unit. If the uplink control channel is arranged in multiple PRB pairs, the uplink control channel is arranged in order from the two ends of the system band.
The uplink control channel includes a channel quality indicator, a scheduling request indicator, and the like.
Since the random access channel and the uplink pilot channel are not related to the present invention, illustration and description thereof are omitted.
FIG. 29 is a diagram showing a schematic configuration of a downlink radio frame in EUTRA (Section 6.2 of Non-Patent Document 2). For example, FIG. 29 shows a schematic configuration of a subframe of a radio frame when a downlink control channel and a downlink shared data channel are time-multiplexed. These resource blocks are hatched and shown. In FIG. 29, the horizontal axis is a time axis and the vertical axis is a frequency axis.
A downlink radio frame includes multiple PRB pairs. The PRB pair is a unit of radio resource allocation or the like, and includes a frequency band (PRB bandwidth) and a time band (2 slots=1 subframe), which have predetermined widths. Basically, 1 PRB pair includes 2 PRBs (PRB bandwidths×slots) which are continuous in the time domain.
In a downlink subframe, 1 PRB includes 12 subcarriers in the frequency domain, and includes 7 orthogonal frequency division multiplexing (OFDM) symbols in the time domain. A system bandwidth is a communication bandwidth of a base station device. In the time domain, there are a slot including 7 OFDM symbols, a subframe including 2 slots, and a radio frame including 10 subframes. A unit including 1 sub-carrier and 1 OFDM symbol is referred to as a resource element. In the downlink radio frame, multiple PRBs corresponding to the system bandwidth are arranged in the frequency direction.
In each subframe of the downlink, at least a downlink shared data channel that is used in transmission of information data and system information and a downlink control channel that is used in control data transmission are arranged. Radio resource allocation of system information and information data within the downlink shared data channel is indicated by the downlink control channel.
A broadcast channel that is used in system information transmission is not shown in FIG. 29, and its arrangement will be described later. The system information includes information necessary for communication by a base station device and a mobile station device, and is periodically transmitted to a number of mobile station devices on the broadcast channel and the downlink shared data channel. Items of the system information arranged in the broadcast channel and the downlink shared data channel are different and the system information arranged in the broadcast channel includes information indicating a system bandwidth and the number of OFDM symbols arranged in the HARQ indicator channel, information for controlling the number of HARQ indicator channels, and the like. The system information arranged in the downlink shared data channel includes uplink and downlink transmission power control information and the like.
The HARQ indicator channel that is used in transmission of response information indicating whether reception of the uplink shared data channel has succeeded and failed is not shown in FIG. 29, and its arrangement will be described later.
Although not shown in FIG. 29, a downlink pilot channel that is used in channel estimation of the downlink shared data channel, the downlink control channel, and the like is arranged in predetermined positions of resource elements distributed in the frequency and time directions in a unit of 1 resource element.
Although not shown in FIG. 29, a control format indicator channel indicating the number of OFDM symbols constituting a downlink control channel is arranged in a predetermined frequency position of a first OFDM symbol.
FIG. 29 shows the case where the downlink control channel is arranged in first, second, and third OFDM symbols of the subframe, and the downlink shared data channel is arranged in other OFDM symbols, but OFDM symbols in which the downlink control channel is arranged are varied in a subframe unit and the downlink control channel may be arranged in only the first OFDM symbol, arranged in the first and second OFDM symbols, or arranged over the first to third OFDM symbols.
The downlink control channel and the downlink shared data channel are not arranged together in the same OFDM symbol. The downlink control channel includes multiple pieces of uplink radio resource allocation information, downlink radio resource allocation information, transmission power command information, and the like.
FIG. 30 is a diagram illustrating a broadcast channel arrangement in a downlink subframe of EUTRA (Section 6.6.4 of Non-Patent Document 2). In FIG. 30, the horizontal axis is a time axis and the vertical axis is a frequency axis. Here, only the downlink shared data channel and the broadcast channel are shown for simplification of description, and the downlink control channel and other channels are not shown.
The broadcast channel is arranged in first to fourth OFDM symbols of a second slot of a first subframe of the radio frame in the time domain and is arranged over 72 subcarriers of the center of the system band, that is, 6 PRBs, in the frequency domain.
Since the broadcast channel is arranged in a predefined time and frequency, a mobile station device can receive the broadcast channel before the initiation of communication with a base station device.
FIG. 31 is a diagram showing orthogonal codes that are used in code multiplexing in the frequency domain for the HARQ indicator channel (physical HARQ indicator channel: PHICH) of EUTRA (Non-Patent Document 2). The HARQ indicator channel is a channel on which response information indicating whether or not a base station device has properly received the uplink shared data channel transmitted from a mobile station device is transmitted. For example, the response information is expressed by 1 bit, wherein the success is indicated by “1” and the failure is indicated by “0”.
In the HARQ indicator channel of EUTRA, the response information bit is modulated by binary phase shift keying (BPSK), and is code-multiplexed in the frequency domain using an orthogonal code in a modulation signal modulated by BPSK. In FIG. 31, for example, a sequence length is 4 orthogonal codes, orthogonal codes of code Nos. 1 to 4 are orthogonal codes that are code-multiplexed with respect to a real axis, orthogonal codes of code Nos. 5 to 8 are orthogonal codes that are code-multiplexed with respect to an imaginary axis, and a maximum of 8 HARQ indicator channels can be multiplexed in the frequency domain using a total of 8 orthogonal codes. As an orthogonal code sequence length, any of “2” and “4” is selected by a length of a cyclic prefix added to the OFDM symbol.
FIG. 32 is a diagram illustrating the correspondence of the uplink shared data channel that is transmitted by a mobile station device and the HARQ indicator channel that is transmitted by a base station device in EUTRA (Non-Patent Document 3).
In FIG. 32, the vertical axis represents a code number used in code multiplexing and the horizontal axis represents a number of a group of HARQ indicator channels (hereinafter, referred to as an “HARQ indicator channel group”) configured by code-multiplexing multiple HARQ indicator channels. For example, FIG. 32 shows the case where the number of HARQ indicator channel groups is 3 when the number of codes is 8. The number of HARQ indicator channel groups is defined by information for controlling the number of PRBs included in a system band and the number of HARQ indicator channels given in the broadcast channel.
An HARQ indicator channel group number and a code number used when a base station device transmits response information to the uplink shared data channel transmitted by a mobile station device are associated with a cyclic shift value of the uplink pilot channel indicated by uplink radio resource allocation that is transmitted by the downlink control channel and a smallest PRB number of the uplink shared data channel allocated to the mobile station device.
The mobile station device recognizes an HARQ indicator channel group number and a code number addressed to its own mobile station device based on information included in the downlink control information.
In EUTRA, it is assumed that one uplink frequency band and one downlink frequency band to be used for communication are managed by one base station device, and it is assumed that the uplink frequency band in which the uplink shared data channel is arranged and the downlink frequency band in which the HARQ indicator channel is arranged are associated in one-to-one relation.
FIG. 33 is a diagram illustrating an HARQ indicator channel arrangement of EUTRA (Non-Patent Document 2). In FIG. 33, the horizontal axis is a time axis and the vertical axis is a frequency axis. For convenience of description, in FIG. 33, the frequency domain represents a system bandwidth, and the time domain represents the downlink control channel arranged in first to third OFDM symbols of a subframe. FIG. 33 shows the case where a code sequence length used in code multiplexing of the HARQ indicator channels is 4 and the number of HARQ indicator channel groups is 2. Also, FIG. 33 shows the case where each HARQ indicator channel is arranged over 3 OFDM symbols.
For simplification of description, the control format indicator channel and the downlink pilot channel are not shown.
In a first OFDM symbol, HARQ indicator channels of an HARQ indicator group 1 are arranged in 4 resource elements in order from a lower side of the frequency domain.
Next, HARQ indicator channels of an HARQ indicator channel group 2 are arranged in 4 resource elements from a resource element next to the resource elements in which the HARQ indicator channels of the HARQ indicator channel group 1 are arranged. Going into details, for example, a signal obtained by multiplying a modulation signal into which response information is BPSK-modulated by each code element of a code of a sequence length 4 is arranged in each resource element.
The same signal as that arranged in the first OFDM symbol is arranged in second and third OFDM symbols. That is, the same signal is multiplexed in the frequency direction. However, when the arrangement is made in the second and third OFDM symbols, an HARQ indicator channel group to be arranged iteratively is uniformly distributed and arranged in the frequency direction.
In addition to the case where the HARQ indicator channel group to be iteratively arranged is distributed and arranged in 3 OFDM symbols as shown in FIG. 33, there is the case where the HARQ indicator channel group to be iteratively arranged is arranged centrally in only a first OFDM symbol. An arrangement to be made by the base station device is indicated using information representing the number of OFDM symbols in which the HARQ indicator channel given in the broadcast channel is arranged. Since the multicast channel and the downlink synchronization channel are not related to the present invention, detailed description thereof is omitted.
FIG. 34 is a diagram illustrating layered OFDMA proposed as a downlink radio access scheme of A-EUTRA (Non-Patent Document 1). In FIG. 34, the horizontal axis is a time axis and the vertical axis is a frequency axis.
A layered OFDMA system band includes multiple continuous frequency bands or multiple discontinuous frequency bands. The case where a situation in which a base station device and a mobile station device perform communication in 1 frequency band and a situation in which a base station device and a mobile station device perform communication simultaneously in multiple frequency bands are mixed within the system band has been proposed.
In terms of mobile station devices, the case where mobile station devices capable of simultaneously receiving only 1 frequency band and mobile station devices capable of simultaneously receiving multiple frequency bands are mixed has been proposed.
Hereinafter, a frequency band unit as described above is referred to as a “subband”. In other words, the subband is a region serving as a unit in which a frequency domain used in communication with a mobile station device is allocated among regions into which radio resources are divided by a base station device in the frequency direction. Sizes of subbands constituting a system band of the base station device may be different respectively.
In FIG. 34, a mobile station device UE1 is allocated subbands 1 to 5, that is, all bands, a mobile station device UE2 is allocated the subband 5, and a mobile station device UE3 is allocated the subbands 1 to 3.
Since each mobile station device is capable of receiving only the allocated subband signal(s), a downlink control channel for each mobile station device is arranged in the subband(s) allocated to each mobile station device.
FIG. 35 is a diagram illustrating a scheme proposed as the uplink radio access scheme of A-EUTRA (Non-Patent Document 1). In FIG. 35, the horizontal axis is a time axis and the vertical axis is a frequency axis. In FIG. 35, there is shown the case where the uplink system band includes 2 subbands, the mobile station device UE1 is capable of transmitting subbands 1 and 2, the mobile station device UE2 is capable of transmitting the subband 2, and the mobile station device UE3 is capable of transmitting the subband 1 if the uplink radio access scheme is SC-FDMA.
As another example, there is shown the case where the mobile station device UE1 is allocated a resource of the subband 1, the subband 2, or the subbands 1 and 2 from the base station device, the mobile station device UE2 is allocated only a resource of the subband 2 from the base station device, and the mobile station device UE3 is allocated only a resource of the subband 1 from the base station device. Even in the uplink like the downlink, the case where the use of a frequency band of the mobile station device is limited and the mobile station device communicates with the base station device in only a limited frequency band has been proposed.    Non-Patent Document 1: 3GPP TSG RAN1 #53, Kansas City, USA, 5-9 May, 2008, R1-081948 “Proposals for LTE-Advanced Technologies”    Non-Patent Document 2: 3GPP TS36.211-v8.3.0 (2008-05), Physical Channels and Modulation (Release 8)    Non-Patent Document 3: 3GPP TS36.213-v8.3.0 (2008-05), Physical Layer Procedures (Release 8)